I think you have done an excellent job on this challenge. When I gave this another look @ 8x6 and compared it to the competition, I gave it an extra point. The fine detail will be lost on many I think. Did you clean this part or was it ever even used?
The main subject being so regular and centered bothered me a bit. Whatever piece of sheetmetal this is, this was a great idea that I would really like to score higher than I am.
I like simple abstract images, but I like them really obsessive... the ridge on the left is closer to the edge of the picture than the one on the right. Also, the circular hole just kisses the edge, which feels awkward to me... if you cropped off just a touch of the right side it would address both of those issues and polish the composition, I think.
Worth pausing to look longer at. I find the composition a touch dull - and the clipping of that circle to the right very annoying - why cut off the only thing that interrupts that flow of rounded squares? It wa a gift for this image, and you've disregarded it. Good sense of feel, but the weighting of areas of interest within frame leaves something to be desired for me.